XFX TS 650w bad design?

I just bought a new system that includes an XFX TS 650w PSU. After testing the system with gaming I noticed the PSU's fan started to speed up to loud enough levels that I could not hear the games I was playing clearly.

Using a watt meter, the peak power usage was only 280-320watts, which is just less than 50% of the PSU's rating.

I checked the GPU/CPU/PSU/Ambient temperatures with the built in sensors and IR thermometer, checked the thermal/current throttling and everything is within normal parameters.

The case has 5 fans and airflow and clearance is fine.

The PSU's fan still becomes loud even when outside of the case under 50% load.

The PSU was returned and replaced with an identical one that has exactly the same problem

I've tested the system with another, cheaper PSU and it's almost silent.

Bad luck x2 or just a flawed PSU design?

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4790K, MSI GTX 980 (system builder version), Gigabyte Z97P-D3

XFX TS 650w bad design?